A magnetic sensor having a coil wound around an amorphous wire is known as one conventional magnetic sensor including a magneto-impedance element. In such a magnetic sensor, for example, a method of extracting the first pulse of an oscillation waveform induced in a coil when a pulse current with a rise time of 5 nanoseconds is passed through an amorphous wire is used in order to obtain a voltage that sensitively varies in proportion to an external magnetic field Hex (see, for example, Patent Document 1).
Patent Document 1 discloses that a feedback coil is wound around an amorphous wire, a feedback circuit is provided, and a negative-feedback current proportional to a sensor output voltage is continuously passed through the feedback coil so as to perform a negative feedback, so that a magnetic sensor exhibiting high-precision characteristics with high linearity and no hysteresis is realized.
Patent Document 1: Japanese Unexamined Patent Application Publication No. 2000-258517.